ANCHORAGE, Alaska (AP) — Dive teams plunged into the icy cold waters of a southeast Alaska inlet Tuesday, searching an area the size of 24 football fields for two cruise ship passengers missing after two sightseeing planes collided.

The Coast Guard has confirmed four fatalities in the collision Monday afternoon near Ketchikan, a popular destination for cruise ships in Alaska. Ten people, all Americans, were injured. The missing passengers were from Canada and Australia.

The Royal Princess, which can carry up to 3,600 people, was among four city-sized cruise ships in the tiny coastal town on Monday.

The cause of the crash in relatively good weather, high overcast skies with light winds was not known.